Process for precipitating hydrometallurgical solutions by means of an improved precipitant.



O. W. MERRILL. PROCESS FOR PRECIPITATING HYDROMETALLUBGICAL SOLUTIONS BY MEANS OF AN 7 IMPROVED PREGIPITANT.

APPLICATION FILED JUNE'Z, 1910.

1,006,865, Patented 001;. 24, 1911.

UNITED STATES armer orrucn.

CHARLES W. MERRILL, 0F BERKELEY, CALIFORNIA.

PROCESS FOR PRECIPITATING HYDROMETALLURGICAL SOLUTIONS BY'MEANS 0F IMPROVED PRECIPITANT.

Specification of Letters Patent.

Patented ea. 24, 1911.

Application filed June 7, 1910. Serial No. 565,548.

of Berkeley, Alameda county, California,

have invented a new and useful Improve ment in Processes for Precipitating Hydrometallurgical Solutions by Means of an Improved Precipitant, of which the following is a specification.

My invention relates to an improved process in preci itating and recovering valuable materials fi'om solution and particularly metals from hydro-metallurgical solutions.

I have 1*. etofore, in Letters Patent of the United States No. 900,186, granted to me upon the 6th day. of October, 1908, described and claimed a process of precipitating and recovering materials from solution, which consisted broadly in adding to the solution to be precipitated a precipitant while in motion, conducting the mixture without rest or without contact with the atmosphere to a filter and then separatingjthe solid from the liquid in said filter. The object of this process was primarily toprecipitate and recover materials from solutions by means of the use of zinc bearing materials as precipitants under conditions which make for increased efliciency as compared 'witl earlier processes,

Now I have discovered as a result of the practi al application of the invention referred to above, that certain zinc bearing materials which are otherwise desirable to use as precipitants, such as zinc fume or dust, are rendered less eflicient and active by reason of the presence of a deterrent coat ing upon the surfaces of the particles thereofcaused in part at least by their .wellknown property of oxidation. In processes 'asheretofore conducted, including the above No. 900,186,' and particularly in the case of cyanid solutions of feeble activity, and those containin very small amounts of metal tobe precip tated, the result of this is to decrease the efficiency ofthe' precipitation because of the fact that this deterrent coa 'ing must be dissolved duringthe process of precipitation before a sufficient contact of the solution and the precipitant results.

The, present improvement relates, therefore, to a process of diminishing the time charge pipe from the receiver.

required in earlier processes to remove the deterrent coating formed as above stated, or in other words to remove this coating of oxid previous to the use of precipitant'in the process by mechanical means.

The present improved process is conducted substantially in the same manner as the process described in the above Letters Patcut and in substantially any form of apparatus applicable in said process.

In the aforesaid Letters Patent I have described a receiver which is provided for the unprecipitated solution, a receiver or mixer for the precipitant, and suitable devices for the conveyance of said solution to a filter. The precipitant may be introduced into the receiver for the unprecipitated solution by means of a suitable duct discharge to asump at the bottom of the receiver, or it may be led to anypoint between said receiver, and the discharge of said filter. In an event the mixture received into the filter is there separated into solids which are retained therein and efliuent liquid or filtrate which is discharged therefrom.

The type of apparatus preferably employed in conducting the process aforesaid is diagrammatically described in the accompanying sheet of drawings forming part of this specification in which- Figure 1 is a diagram showing the devices for the treatment of the precipitant, connected with the suction pipe of the pump; and Fig. 2 adiagram showing the same device connected with the discharge at the top and is discharged at the bottom into the receiver E for the precipitated solution by means ofthe pipe G; J is the dis- In Fig. 1, A is any suitable paratus.

grinding ap- Inpractice, the grinding apparatus may beinterposed at any point between the re ceivingtank'for'unprecipitated solution and the filter, or it may discharge under pres sure by meansof an independent inlet directly. to the filter.

In cases of particularly low strength cyanid solutions, or cyanid solutions containing very small amounts of metal to be precipitated, which, under ordinary. conditions, are

difficult to precipitate by means of metallic replacement, it may be particularly desirable to grind the precipitant in contact with all of the solution to be precipitated thus not only abrading off the deterrent coating,

but also increasing the intensity and duration of the agitation of the mixture. That is, to pass all of the solution so to be precipitated through a closed grinding apparatus such as a tube mill preferably interposed between the inletof a suction pipe of a pump and said pump, or between the point of discharge from said pump and the inlet to said filter, or 11L case a gravity flow is used, at any point between the receiver for unprecipitated solution andthe discharge of the filter.

The method of operation is as follows:

The precipitant is fed through the pipe I into the receivers Z; thence it is fed through the pipeH into the tank U. The solution to be treated is fed into. the tank U through the pipe 13. The pump is continuously op: erated, and causes the liquid to flow through the suction pipe C and through the discharge pipe D into the filter F whence the filtrate flows through the pipe G into the tank E from which it is discharged through the pipe J into any suitable receptacle. The grinding apparatus A which is shown in Fig. 1 connected with the suction pipe, and in Fig. 2 with the discharge pipe of the pump P, causes the particles of the precipitant to be thoroughly abraded and constantly intermingled with the solution as it passes through the apparatus-on its way to the filter. The gist of the present form of treatment consists in the fact that the precipitant is subjected to a mechanical treatment whilepassing with the solution.

through the apparatus employed for producing the mechanical treatment.

I do not limit myself to any particular method of, or apparatus for, conducting the unprecipitated solution from the container and while the solution and in which the dissolution takes place to the filter, nor do I limit myself to adding the precipitant at any particular point along the duct through which the effluent unprecipitated solution passes; nor do I limit my self to the use of the precipitant in a liquid or emulsified form, but'may add it dry.

In practice, if desired, a liquid may be added to the precipitant before or after it is introduced into the receiver Z, or if an emulsion of the precipitant be used it may be fed directly into the receiver. In case the precipitant is in a dry form, if necessary it may be reduced before the introduction into the receiver to the form of a fine powder.

I claim as my invention:

1. The process for precipitating and recovering material from solution which consists in precipitating the material from said solutionwhile in motion by a suitable precipitant, subjecting the precipitant to mechanical treatment for the removal of any deterrent coating from the surface of the particles thereof, conducting the mixture without rest to a filter, and separating the solid from the liquid in said filter.

2. The process for precipitating and recoveringniaterial from solution which consists in adding a suitable precipitant thereto, precipitant are being conveyed to a filter, subjecting the precipitant to mechanical treatment for the removal of any deterrent coating from the surface of the particles thereof, and separating the solid from the liquid in said filter.

3,. The process for precipitating and recovering material from solution which consists in conveying said solution to, a pressure filter, subjecting the precipitant to mechanical treatment for the removal of any deterrent coating from the surface of the particlcs thereof, and forcing the precipitant di rectly into said pressure filter with said solution, and separating the solid from the liquid in said filter.

i. The process for precipitating and recovering materials from solution which consists in adding a suitable precipitant thereto, and while the solution and precipitant are being conveyed to a filter subjecting the precipitant to mechanical treatment for the removal of any deterrent coating from the surface of the particles thereof, forcing the mixture into the top of the pressure filter, and separating the solid from the liquid in said filter.

5. The process for precipitating and recovering material from solution which consists in adding a suitable precipitant to a solution in motion at a .point adjacent to the outlet of said solution from a receiver, subjecting the precipitant to mechanical treatment for the removal of any deterrent coating from the surface of the particles thereof, forcing the inixture through a presmo est sure filter, and-separating the. solid from the liquid in said filter.

6. The process for precipitating and recovering material from solution which'con sists in adding a suitable precipitant to said solution in-motion, subjecting the precipitant to a mechanical .treatmentfor the re moval of any deterrent coating from the surface ofthe particles thereof, conveying the mixture .to a filter, and separating the solid from theliquid in said filter, all-the "while excluding the mixture from contact.

with the atmosphere.

-7. The process .fr precipitating and recovering material from solution which con? ,sists in adding a suitable precipitant to saidsolution in motion at a' point adjacent to the suction pipe of a pump, subjecting the precipitant to mechanical treatment for the removal ofany deterrent coating from the surface of the particles thereof, thence pumping the mixture to the top of the pressure filter, and separating the solid from the liquid in said filter.

8. The process for-precipitating and recovering material from solution which con-. sists 'in adding a suitable precipitant to saidsolution in motion at apoint adjacent to the suction pipe of thepump, subjecting the precipitant to mechanical treatment for the removal of any deterrent coating from the surface ofthe particles fthereof, thence pumping the mixture to the to of a pres'-' sure filter, separating the solid. rom the liquid in'said filter, all the while excluding-the mixturejfrom contact with the atmosphere; 9. The processfor precipitating and re-. covering metals from cyanid solutions which consists in adding an emulsion of a suitable zinc precipitant to said solution while in -motion, subjecting the zinc precipitant to 'phere.

mechanical treatment forthe removal of. any deterrent coatin particles thereo conducting the mixture withoutrest to a filter, and separating the solid from the liquid in said filter.

l0. The'process' for precipitating" and recovering metals from cyanid solutions which consists in adding an emulsion of a suitable zinc precipitant to said solution while in.

motion, subjecting the zinc precipitant to mechanical treatment for the rem al of any deterrentcoating from the surface of the particles thereof, conductingthe mixture to a filter, and separating the solid from the liquid in said filter, all the while excluding the mixture from contact with the atmos- 11. The process of precipitating and "recovering metals from cyanid solutions which consists in mixing a suitable zinc precipitant with a liquid 'in a receiver, adding a liquid continuously to said receiver, discharging the ..emulsiojn from said recei r into said solution in motion, subjectingthe from the surface of the.

zinc precipitant to mechanical treatment for the-removal of any deterrent coating from the surface of the particles thereof, conductingthe mixture without rest to a filter, and separating the solid from the liquid in said filter.

12. The process of precipitating and recover ng metals from cyanid solutions which consists in mixing a suitable zinc precipitant with a liquid in a receiver, adding a liquid continuously to said receiver, discovering metals from cyanid solutions which consists in adding to the solution a suitable metallic precipitant for precipitating gold and other unprecipitated metals, sub ecting the metallic precipitant to mechanical treatment for the removal of any deterrent coat ing from the surface of the particles thereof, coiiducting the mixture to a filter, and separating'the solid from the liquid in said filter. 14. The process for precipitating and re- .covering metals from cyanid solutions which consists in first adding a zinc precipitant to said solutions, subjecting the zinc precipi- "tant to mechanical treatment for the removal of any deterrent coating from the surface of the particles thereof, conducting the mixture to a filter, and separating the solid from the liquid in said filter.

1'5. The process for precipitating and recovering metals from cyanid solutions which consists in first addin a zinc precipitant to said solution, subjecting the zinc precipitant to mechanical treatment for the removal of any deterrent coating from the surface of the particles thereof, conducting the mixture without rest to a. filter, and

piepa'rating the solid from the liquid in said lter.

' '16. The process for pre'cipitating and recovering'met'als from cyanid solutions which consists in first adding a zinc precipitant to said solution, s'ubjecting the zinc precipitant to. mechanical treatment for the removal of any deterrent coating from the surface of the particles thereof, conducting the mixture, excluding the atmosphere therefrom, to a filter, and separating the solid from the liquid in said filter.

17. The process for precipitating andrecovering metals from cyanid. solutions which consists in first adding finely divided zinc to said solution, subjecting, the finely di- Hded zinc to mechanical treatment for-"the .& 1,006,865

removal of any deterrent coating from the as my invention, I have signed my name in surface of the particles thereof, conducting presence of two witnesses, this third day the mixture without rest and without conof June 1910.

tact with the atmosphere to a filter,- and -CHARLES W.-MERRILL. 5 separating the solid from the liquid in said Witnesses:

filter. Wmmnn PARKER BUTLER.

In testimony, that I claim the foregoing C ARLES ENGEL. 

